Energy interactions

In thermodynamics 2 (two) types of energy are considered. One is heat and the other is work. Both of these energies may interact at the boundary of the system. When work energy interacts at the boundary and converts to work only, we need not pay attention to its quality as final form of energy is work only. Heat to heat interactions always involve degradation. Work converted to heat is not useful, we call it as dissipation of energy. In thermodynamics basic interest is conversion of heat into work.

Laws of Thermodynamics

Interactions of energy at system boundary is governed by certain laws. There are 4 basic laws in classical thermodynamics. These are: Zeroth law, first law, second law and third law of thermodynamics. Apart from these laws, there is another law applied to irreversible thermodynamics developed by Onsagar in the year 1957. This law is termed as fourth law of thermodynamics.

Table 1.4 presents the laws of thermodynamics along with the scientists associated with their invention and year of invention.

Thermodynamic Laws	Scientists/Researchers	Year
Zeroth Law	Fowler and Guggenheim	1939
First Law	Joule, Mayer, Thompson and Colding	1845
Second Law	Carnot	1824
Third Law	Nernst	1907
Fourth Law	Onsagar	1968

Table 1.4: Different Thermodynamic Laws